1. Technical Field
The technical field relates to an angular velocity sensor for use in, for example, a mobile device or a vehicle, and to an angular velocity detection device included in the sensor.
2. Background Art
FIG. 17 is a perspective view of an angular velocity detection device used in a conventional angular velocity sensor. Angular velocity detection device 1 includes frame body 2, transverse beam 3, arms 4, 5, 6, and 7, weights 8, 9, 10, and 11, driver 12, monitor 13, and detectors 14, 15. Transverse beam 3 is suspended by frame body 2 in the direction of the X axis where the X, Y and Z axes are orthogonal to each other. One end of each of arms 4 and 5 is supported by transverse beam 3 and arms 4 and 5 extend in the positive direction of the Y axis. Weights 8 and 9 are disposed at another end of each of arms 4 and 5, respectively. One end of each of arms 6 and 7 is supported by transverse beam 3 and arms 6 and 7 extend in the negative direction of the Y axis. Weights 10 and 11 are disposed at another end of each of arms 6 and 7, respectively. Driver 12 applies an AC voltage to arm 4 so as to generate a piezoelectric effect, thereby vibrating arm 4 in the direction of the X axis. This vibration causes arms 5, 6, and 7 to resonate in the direction of the X axis. Monitor 13 detects the displacements of arms 4, 5, 6, and 7 in the direction of the X axis. Detectors 14 and 15 output sensing signals, which are generated on arms 6 and 7 due to the piezoelectric effect and are caused by the Coriolis force when an angular velocity is applied to angular velocity detection device 1. From these sensing signals, displacements in the direction of the Y or Z axis are detected.